Table of Contents
Using data available up to the: 2020-05-04
Note that it takes time for infection to cause symptoms, to get tested for SARS-CoV-2 infection, for a positive test to return and ultimately to enter the case data presented here. In other words, today’s case data are only informative of new infections about two weeks ago. This is reflected in the plots below, which are by date of infection.
Expected daily confirmed cases by region
Figure 1: The results of the latest reproduction number estimates (based on estimated confirmed cases with a date of infection on the 2020-04-23) in the United States of America, stratified by state, can be summarised by whether confirmed cases are likely increasing or decreasing. This represents the strength of the evidence that the reproduction number in each region is greater than or less than 1, respectively (see the methods for details). Regions with fewer than 40 confirmed cases reported on a single day are not included in the analysis (light grey).
National summary
Summary (estimates as of the 2020-04-23)
Table 1: Latest estimates (as of the 2020-04-23) of the number of confirmed cases by date of infection, the expected change in daily confirmed cases, the effective reproduction number, the doubling time (when negative this corresponds to the halving time), and the adjusted R-squared of the exponential fit. The mean and 90% credible interval is shown for each numeric estimate.| Estimate | |
|---|---|
| New confirmed cases by infection date | 33914 (33255 – 34405) |
| Expected change in daily cases | Increasing |
| Effective reproduction no. | 1.1 (1.1 – 1.1) |
| Doubling/halving time (days) | 40 (29 – 64) |
| Adjusted R-squared | 0.74 (0.67 – 0.82) |
Confirmed cases, their estimated date of infection, and time-varying reproduction number estimates
Figure 2: A.) Confirmed cases by date of report (bars) and their estimated date of infection. B.) Time-varying estimate of the effective reproduction number. Light ribbon = 90% credible interval; dark ribbon = the 50% credible interval. Estimates from existing data are shown up to the 2020-04-23 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The vertical dashed line indicates the date of report generation.
Time-varying rate of growth and doubling time
Figure 3: A.) Time-varying estimate of the rate of growth, B.) Time-varying estimate of the doubling time in days (when negative this corresponds to the halving time), C.) The adjusted R-squared estimates indicating the goodness of fit of the exponential regression model (with values closer to 1 indicating a better fit). Estimates from existing data are shown up to the 2020-04-23. Light ribbon = 90% credible interval; dark ribbon = the 50% credible interval. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence.
Regional Breakdown
Data availability
- Case counts by date, stratified by region, were downloaded from a publically available source curated by Johns Hopkins University (“2019 Novel Coronavirus Covid-19 (2019-nCoV) Data Repository” 2020; Abbott et al. 2020).
- Case onset dates were estimated using case counts by date of report and a distribution of reporting delays fitted to a publically available line-list of international cases (Xu et al., n.d.; Abbott et al. 2020).
Limitations
- Line-list data to inform a State specific estimates of the reporting delay were not available.
- Regions are only included if at least 40 confirmed cases have been reported on a single day.
Summary of latest reproduction number and confirmed case count estimates by date of infection
Figure 4: Confirmed cases with date of infection on the 2020-04-23 and the time-varying estimate of the effective reproduction number (light bar = 90% credible interval; dark bar = the 50% credible interval.). Regions are ordered by the number of expected daily confirmed cases and shaded based on the expected change in daily confirmedcases. The horizontal dotted line indicates the target value of 1 for the effective reproduction no. required for control and a single case required for elimination.
Reproduction numbers over time in the six regions expected to have the most new confirmed cases
Figure 5: Time-varying estimate of the effective reproduction number (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in the regions expected to have the highest number of new confirmed cases. Estimates from existing data are shown up to the 2020-04-23 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The horizontal dotted line indicates the target value of 1 for the effective reproduction no. required for control. The vertical dashed line indicates the date of report generation.
Confirmed cases and their estimated date of infection in the six regions expected to have the most new confirmed cases
Figure 6: Confirmed cases by date of report (bars) and their estimated date of infection (light ribbon = 90% credible interval; dark ribbon = the 50% credible interval) in the regions expected to have the highest number of new confirmed cases. Estimates from existing data are shown up to the 2020-04-23 from when forecasts are shown. These should be considered indicative only. Confidence in the estimated values is indicated by translucency with increased translucency corresponding to reduced confidence. The vertical dashed line indicates the date of report generation.
Reproduction numbers over time in all regions
